Low-carbon high-performance concrete and preparation method thereof

Abstract

The invention discloses low-carbon high-performance concrete and a preparation method thereof. The concrete is prepared from the following raw materials in parts by weight: 76-146 parts of a cementing material A and / or 76-146 parts of a cementing material B and 25-50 parts of an exciting agent, 374 to 424 parts of cement; 60-70 parts of fly ash; 750-772 parts of machine-made medium sand; 900 to 930 parts of stone; 9.5 to 9.81 parts of a water reducing agent and 135 to 142 parts of water; wherein the total part by weight of the cementing material A and / or the cementing material B, the exciting agent and the cement is 560-570, the cementing material A is compound superfine steel slag powder with the CaO mass content being larger than or equal to 44%, the cementing material B is carbonized compound superfine steel slag powder with the SiO2 mass content being larger than or equal to 32%, and the exciting agent comprises gypsum and micro-silicon powder. According to the concrete prepared by utilizing the double-excitation synergistic effect of the superfine steel slag powder, the gypsum and the silica fume, the building solid waste can be fully utilized, the compressive strength of the concrete is enhanced, the cement consumption and the energy consumption of building materials are reduced, the CO2 emission is reduced, and meanwhile, the working performance and the mechanical performance of the concrete can be ensured to meet the construction requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete, and in particular to a low-carbon high-performance concrete and a preparation method thereof. Background Art

[0002] As global urbanization accelerates, demand for concrete, a core material in the construction industry, continues to climb. At the same time, the building materials industry, a traditionally high-carbon industry, faces significant pressure to transform. Concrete, the world's most widely used building material, generates 8-10% of global anthropogenic carbon emissions through its production process, with cement clinker production contributing approximately 60%. To reduce concrete's carbon emissions, existing technologies often use carbon powder as a partial cement substitute. While this can reduce carbon emissions, its raw material relies on blast furnace slag. However, slag resources are limited by steel production capacity, with global annual production reaching only 600 million tons, far from meeting the needs of the concrete industry.

[0003] Steel slag, with its chemical composition similar to that of Portland cement, theoretically offers the potential to replace mineral powder. However, its practical application has long faced technical bottlenecks. The cementitious activity of steel slag is significantly lower than that of mineral powder, primarily due to its complex mineral composition and high proportion of inert phases. Converting steel slag into a high-performance concrete admixture presents a dual challenge, addressing both resource shortages and environmental pollution. Summary of the Invention

[0004] In response to the defects in the existing technology, the present application provides a low-carbon, high-performance concrete and its preparation method to solve the technical problems in the existing technology such as high carbon emissions in the concrete production process, easy environmental pollution caused by steel slag treatment, insufficient activation of steel slag in concrete, and limited application efficiency.

[0005] In order to achieve the purpose of the above invention, the technical solution provided by the present invention is as follows:

[0006] A low-carbon, high-performance concrete comprises the following raw materials, in parts by weight: 76-146 parts of cementitious material A and / or 76-146 parts of cementitious material B, 25-50 parts of an activator; 374-424 parts of cement; 60-70 parts of fly ash; 750-772 parts of machine-made medium sand; 900-930 parts of gravel; 9.5-9.81 parts of a water reducer, and 135-142 parts of water; wherein the total weight of the cementitious material A and / or cementitious material B, the activator, and the cement is 560-570 parts, the cementitious material A is a composite ultrafine steel slag powder having a CaO mass content of 44% or more, the cementitious material B is a carbonized composite ultrafine steel slag powder having a SiO2 mass content of 32% or more, and the activator comprises gypsum and microsilica fume.

[0007] In one embodiment, the cementitious material A comprises the following chemical components by mass: 44.82% CaO, 28.90% SiO2, 10.79% Fe2O3 and 7.87% Al2O3.

[0008] In one embodiment, the cementitious material B comprises the following chemical components by mass: 42.44% CaO, 32.1% SiO2, 9.79% Fe2O3 and 8.64% Al2O3.

[0009] In one embodiment, the gypsum is desulfurized gypsum with a particle size of less than 0.074 mm, and the average particle size of the microsilica powder is 0.2 μm.

[0010] In one embodiment, the cement is Portland cement or ordinary Portland cement, and the strength grade of the cement is greater than or equal to 52.5.

[0011] In one embodiment, the fly ash is Class II C, and the fly ash sample passes through a 45 μm square hole sieve, and the weight of the coarse particles remaining on the sieve accounts for no more than 2.5% of the total weight of the fly ash.

[0012] In one embodiment, the specific surface area of ​​the ultrafine steel slag powder in the cementitious material A and the cementitious material B is 600m 2 / kg or more.

[0013] The present application also provides a method for preparing the above-mentioned low-carbon high-performance concrete, comprising the following steps:

[0014] S1. Take 76-146 parts of cementitious material A and / or 76-146 parts of cementitious material B, 25-50 parts of activator, 374-424 parts of cement, 60-70 parts of fly ash, 750-772 parts of machine-made medium sand, 900-930 parts of gravel, 9.5-9.81 parts of water reducer, and 135-142 parts of water in a mass ratio; mix the remaining materials except water and water reducer uniformly under mechanical stirring to obtain powder A;

[0015] S2. Add a water reducer into water and dissolve it to obtain a water reducer aqueous solution B. Mix the powder A and the water reducer aqueous solution B with stirring to obtain a low-carbon high-performance concrete mixture C.

[0016] S3. Pour the low-carbon high-performance concrete mixture C into a mold for casting, vibrate and shape it, and then cure it for 28 days to obtain low-carbon high-performance concrete.

[0017] Compared with the prior art, this application has at least the following beneficial effects:

[0018] The present invention arranges compounded ultrafine steel slag powder with a CaO mass content of ≥44%, compounded ultrafine steel slag powder with a SiO2 mass content of ≥32%, an activator including gypsum and microsilica powder, and cement in the total adhesive of low-carbon, high-performance concrete raw materials, and uses ultrafine steel slag powder to completely replace the mineral powder in the total adhesive of low-carbon, high-performance concrete raw materials in the prior art. The preparation of steel slag powder is a grinding process in which the steel slag powder is ground into ultrafine particles, breaking its dense glass coating layer and releasing the activity of dicalcium silicate and calcium ferrite; then the ultrafine steel slag powder is compounded to construct a "Fe2O3-SiO2-Al2O3" ternary synergistic system, which significantly improves the efficiency of the volcanic ash reaction; finally, CO2 pressure is applied to the compound material for carbonization to form a microstructure of "nano-CaCO3-coated active core", which not only inhibits volume expansion but also accelerates hydration through the seed effect of calcium carbonate. The modified ultrafine steel slag powder obtained can not only achieve 100% replacement of mineral powder with steel slag powder, but also reduce carbon emissions from concrete, while sequestering CO2 through the carbonization process.

[0019] The modified ultrafine steel slag powder in the present invention completely replaces the mineral powder in low-carbon high-performance concrete, using desulfurized gypsum and microsilica as activators. The main mineral components of the steel slag powder are dicalcium silicate, tricalcium silicate, tetracalcium aluminoferrite and RO phase. The synergistic effect of sulfate activation of gypsum and alkali activation of microsilica can significantly improve the activity of steel slag in concrete: desulfurized gypsum releases SO4 after dissolution. 2- In an alkaline environment, it reacts with the aluminum dissolved in the steel slag to form needle-shaped ettringite, which fills the pores, improves the density and early strength, and at the same time, the gypsum hydrolysis increases the liquid phase Ca 2+ concentration, accelerating the hydrolysis of dicalcium silicate and tricalcium silicate in steel slag; microsilica fume reacts with Ca(OH)2 produced by steel slag hydration through a volcanic ash reaction with high-activity SiO2 to generate a dense CSH gel with a low calcium-silicon ratio, consuming Ca(OH)2 to reduce porosity. At the same time, based on its high specific surface area, it can serve as a crystal nucleus site to accelerate the crystallization of hydration products, shorten the induction period, and fill micropores to refine the structure. Desulfurized gypsum and microsilica fume synergistically form a triple mechanism of "sulfate excitation-volcanic ash reaction-microaggregate filling": desulfurized gypsum maintains an alkaline environment and stimulates the activity of the aluminum phase, and microsilica fume consumes Ca(OH)2 to promote the continuous hydrolysis of steel slag, while reducing the Ca / Si ratio of CSH and optimizing the gel structure. The final product is mainly composed of interwoven CSH gel and calcium aluminoferrite network, which significantly improves density and strength. The OH produced by steel slag powder during cement hydration - Under erosion, the surface dense layer is destroyed, and C2S and C3S continue to hydrate to replenish Ca 2+ and SiO4 4- , while Mg in RO phase 2+ 、Fe 2+ Participate in the formation of hydrated magnesium silicate gel. SO4 of desulfurized gypsum 2- Further with Al dissolved in slag3+ The combination promotes AFt growth, while the nanoparticles of microsilica refine the pore size and, together with the CSH gel, optimize the microstructure. The amorphous CSH gel and the needle-like AFt crystals intergrow to form a dense "gel-encased crystal" network, and the later-generated Friedel salt and hydrated magnesium silicate further fill the pores.

[0020] The low-carbon, high-performance concrete with the synergistic effect of modified ultrafine steel slag powder and dual excitation in the present invention can make full use of construction solid waste. The steel slag powder will increase its activity under the synergistic excitation of desulfurized gypsum and microsilica powder, thereby enhancing the compressive strength of concrete; alleviating the shortage of slag powder resources, reducing cement usage and energy consumption of building materials, and reducing carbon dioxide gas emissions, while also ensuring that the working performance and mechanical properties of concrete meet construction requirements.

[0021] The method for preparing low-carbon, high-performance concrete with the synergistic effect of modified ultrafine steel slag powder and double excitation in the present invention has a simple process flow, low production cost, and simple construction. It can prepare low-carbon, high-performance concrete with an expansion of 500-530 mm and a 28d concrete compressive strength of 83.7-99.9 MPa. The low-carbon, high-performance concrete prepared by this method has the advantages of good workability, high compressive strength, low cost, environmental protection, pollution-free, and low energy consumption. DETAILED DESCRIPTION

[0022] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention is described below by way of specific embodiments. However, it should be understood that these descriptions are merely illustrative and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the present invention.

[0023] The terms used in this disclosure are for the purpose of describing specific embodiments only and are not intended to limit the disclosure. As used in this disclosure and the appended claims, the singular forms "a," "an," "the," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0024] It should be understood that although the terms first, second, third, etc. may be used in this disclosure to describe various information, such information should not be limited to these terms and should not be understood to indicate or imply relative importance. These terms are only used to distinguish information of the same type from each other. For example, first information may also be referred to as second information, and similarly, second information may also be referred to as first information without departing from the scope of this disclosure. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining."

[0025] In the description of the present invention, unless otherwise specified and limited, it should be noted that the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a mechanical connection or the internal communication between two components. It can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances.

[0026] In order to better understand the technical solution of the present invention, the present invention is described in detail below with reference to embodiments and comparative examples.

[0027] Example 1:

[0028] A low-carbon, high-performance concrete in which modified ultrafine steel slag powder completely replaces mineral powder is obtained by the following preparation steps:

[0029] Step 1: Take 76 parts of cementitious material A, 50 parts of activator, 374 parts of cement, 70 parts of fly ash, 772 parts of machine-made medium sand, 930 parts of gravel, 9.81 parts of water reducer, and 142 parts of water in proportion by mass; mix the remaining materials except water and water reducer uniformly under mechanical stirring to obtain powder A;

[0030] Step 2: adding a water reducer into water to dissolve it to obtain a water reducer aqueous solution B, and mixing the powder A and the water reducer aqueous solution B evenly under stirring to obtain a low-carbon high-performance concrete mixing material C;

[0031] Step 3: Pour the low-carbon high-performance concrete mixture C into a mold for casting, vibrate and shape it, and then cure it for 28 days to obtain low-carbon high-performance concrete.

[0032] Example 2:

[0033] A low-carbon, high-performance concrete in which modified ultrafine steel slag powder completely replaces mineral powder is obtained by the following preparation steps:

[0034] Step 1: Take 76 parts of cementitious material B, 50 parts of activator, 374 parts of cement, 70 parts of fly ash, 772 parts of machine-made medium sand, 930 parts of gravel, 9.81 parts of water reducer, and 142 parts of water in proportion by mass; mix the remaining materials except water and water reducer uniformly under mechanical stirring to obtain powder A;

[0035] Step 2: adding a water reducer into water to dissolve it to obtain a water reducer aqueous solution B, and mixing the powder A and the water reducer aqueous solution B evenly under stirring to obtain a low-carbon high-performance concrete mixing material C;

[0036] Step 3: Pour the low-carbon high-performance concrete mixture C into a mold for casting, vibrate and shape it, and then cure it for 28 days to obtain low-carbon high-performance concrete.

[0037] Example 3:

[0038] A low-carbon, high-performance concrete in which modified ultrafine steel slag powder completely replaces mineral powder is obtained by the following preparation steps:

[0039] Step 1: Take 38 parts of cementitious material A, 38 parts of cementitious material B, 50 parts of activator, 374 parts of cement, 70 parts of fly ash, 772 parts of machine-made medium sand, 930 parts of gravel, 9.81 parts of water reducer, and 142 parts of water in proportion by mass; mix the remaining materials except water and water reducer uniformly under mechanical stirring to obtain powder A;

[0040] Step 2: adding a water reducer into water to dissolve it to obtain a water reducer aqueous solution B, and mixing the powder A and the water reducer aqueous solution B evenly under stirring to obtain a low-carbon high-performance concrete mixing material C;

[0041] Step 3: Pour the low-carbon high-performance concrete mixture C into a mold for casting, vibrate and shape it, and then cure it for 28 days to obtain low-carbon high-performance concrete.

[0042] Comparative Example 1:

[0043] A low-carbon, high-performance concrete in which modified ultrafine steel slag powder completely replaces mineral powder is obtained by the following preparation steps:

[0044] Step 1: Take 424 parts of cement, 70 parts of fly ash, 76 parts of mineral powder, 772 parts of machine-made medium sand, 930 parts of gravel, 9.81 parts of water reducer, and 142 parts of water in proportion by mass; mix the remaining materials except water and water reducer under mechanical stirring to obtain powder A;

[0045] Step 2: adding a water reducer into water to dissolve it to obtain a water reducer aqueous solution B, and mixing the powder A and the water reducer aqueous solution B evenly under stirring to obtain a low-carbon high-performance concrete mixing material C;

[0046] Step 3: Pour the low-carbon high-performance concrete mixture C into a mold for casting, vibrate and shape it, and then cure it for 28 days to obtain low-carbon high-performance concrete.

[0047] Comparative Example 2:

[0048] A low-carbon, high-performance concrete in which modified ultrafine steel slag powder completely replaces mineral powder is obtained by the following preparation steps:

[0049] Step 1: Take 126 parts of cementitious material A, 374 parts of cement, 70 parts of fly ash, 772 parts of machine-made medium sand, 930 parts of gravel, 9.81 parts of water reducer, and 142 parts of water in proportion by mass; mix the remaining materials except water and water reducer uniformly under mechanical stirring to obtain powder A;

[0050] Step 2: adding a water reducer into water to dissolve it to obtain a water reducer aqueous solution B, and mixing the powder A and the water reducer aqueous solution B evenly under stirring to obtain a low-carbon high-performance concrete mixing material C;

[0051] Step 3: Pour the low-carbon high-performance concrete mixture C into a mold for casting, vibrate and shape it, and then cure it for 28 days to obtain low-carbon high-performance concrete.

[0052] Comparative Example 3:

[0053] A low-carbon, high-performance concrete in which modified ultrafine steel slag powder completely replaces mineral powder is obtained by the following preparation steps:

[0054] Step 1: Take 126 parts of cementitious material B, 374 parts of cement, 70 parts of fly ash, 772 parts of machine-made medium sand, 930 parts of gravel, 9.81 parts of water reducer, and 142 parts of water in proportion by mass; mix the remaining materials except water and water reducer under mechanical stirring to obtain powder A;

[0055] Step 2: adding a water reducer into water to dissolve it to obtain a water reducer aqueous solution B, and mixing the powder A and the water reducer aqueous solution B evenly under stirring to obtain a low-carbon high-performance concrete mixing material C;

[0056] Step 3: Pour the low-carbon high-performance concrete mixture C into a mold for casting, vibrate and shape it, and then cure it for 28 days to obtain low-carbon high-performance concrete.

[0057] The raw material components of each embodiment and comparative example are shown in Table 1:

[0058] Table 1:

[0059]

[0060]

[0061] The high performance concrete obtained in each embodiment and comparative example is shown in Table 2:

[0062] Table 2:

[0063]

[0064] As shown in Tables 1 and 2, Comparative Examples 1, 2, and 3 show that without the addition of an activator, when Material A or Material B completely replaces the mineral powder and partially replaces the cement, the concrete expansion is slightly reduced, while the 28-day compressive strength remains essentially unchanged. Comparative Example 1, Examples 1, and 2 show that when an activator is added, Material A or Material B can completely replace the mineral powder, and the concrete expansion is slightly increased, while the compressive strength is significantly improved. Comparative Examples 2 and 3, as well as Examples 1 and 2, show that the carbonized composite ultrafine steel slag powder slightly increases the concrete expansion and 28-day compressive strength. Comparative Example 2 and Example 1, and Comparative Example 3 and Example 2 show that the addition of an activator slightly increases the concrete expansion and significantly increases the 28-day compressive strength. Examples 1, 2, and 3 show that the co-addition of two ultrafine steel slag powders in a 1:1 ratio results in essentially unchanged concrete expansion, with a 28-day compressive strength between the two groups of experiments in which the steel slag powder was added alone. In summary, the low-carbon, high-performance concrete prepared by the present invention, by modifying ultrafine steel slag powder and adding an activator, allows the modified ultrafine steel slag powder to completely replace mineral powder, improving the concrete's expansion and 28-day compressive strength. It is also low-cost, environmentally friendly, pollution-free, low-energy, and easy to prepare. Ultrafine steel slag concrete offers significant cost advantages over conventional concrete, addressing the shortage of slag powder resources while enabling the extensive use of steel slag, improving the ecological environment, and promoting the green, circular development of steel enterprises.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solutions of the present invention. They should all be included in the scope of the technical solutions for which protection is sought in the present invention.

Claims

1. A low-carbon high-performance concrete, characterized in that: The invention comprises the following raw materials in parts by weight: 76-146 parts of cementitious material A and / or 76-146 parts of cementitious material B, 25-50 parts of activator; 374-424 parts of cement; 60-70 parts of fly ash; 750-772 parts of machine-made medium sand; 900-930 parts of gravel; 9.5-9.81 parts of water reducer, and 135-142 parts of water; wherein, the total weight of cementitious material A and / or cementitious material B, activator and cement is 560-570 parts, the cementitious material A is a compound ultrafine steel slag powder with a CaO mass content of ≥44%, the cementitious material B is a compound ultrafine steel slag powder after carbonization and with a SiO2 mass content of ≥32%, and the activator includes gypsum and microsilica powder.

2. The low-carbon high-performance concrete according to claim 1, characterized in that The cementitious material A comprises the following chemical components by mass: 44.82% of CaO, 28.90% of SiO2, 10.79% of Fe2O3 and 7.87% of Al2O3.

3. The low-carbon high-performance concrete according to claim 1, characterized in that The cementitious material B includes the following chemical components by mass: 42.44% CaO, 32.1% SiO2, 9.79% Fe2O3 and 8.64% Al2O3.

4. The low-carbon high-performance concrete according to claim 1, characterized in that The gypsum is desulfurized gypsum with a particle size of less than 0.074 mm, and the average particle size of the microsilica powder is 0.2 μm.

5. The low-carbon high-performance concrete according to claim 1, characterized in that: The cement is silicate cement or ordinary silicate cement, and the strength grade of the cement is greater than or equal to 52.

5.

6. The low-carbon high-performance concrete according to claim 1, characterized in that The fly ash is of Class II C. When the fly ash sample passes through a 45 μm square hole sieve, the weight of the coarse particles remaining on the sieve accounts for no more than 2.5% of the total weight of the fly ash.

7. The low-carbon high-performance concrete according to claim 1, characterized in that: The water reducer is a polycarboxylate water reducer, and the water is deionized water.

8. The low-carbon high-performance concrete according to claim 1, characterized in that: The specific surface area of ​​the ultrafine steel slag powder in cementitious materials A and B is 600m 2 / kg or more.

9. A method for preparing low-carbon high-performance concrete according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Take 76-146 parts of cementitious material A and / or 76-146 parts of cementitious material B, 25-50 parts of activator, 374-424 parts of cement, 60-70 parts of fly ash, 750-772 parts of machine-made medium sand, 900-930 parts of gravel, 9.5-9.81 parts of water reducer, and 135-142 parts of water in a mass ratio; mix the remaining materials except water and water reducer uniformly under mechanical stirring to obtain powder A; S2. Add a water reducer into water and dissolve it to obtain a water reducer aqueous solution B. Mix the powder A and the water reducer aqueous solution B with stirring to obtain a low-carbon high-performance concrete mixture C. S3. Pour the low-carbon high-performance concrete mixture C into a mold for casting, vibrate and shape it, and then cure it for 28 days to obtain low-carbon high-performance concrete.

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